Field of the Invention
The present invention relates to a plunger pump that transfers fluid by rotating and reciprocating a plunger in a cylinder chamber to let a suction port and a discharge port alternately communicate with the cylinder chamber.
Description of the Prior Art
As disclosed in JP 2001-248543 A and JP 2008-51392 A, for example, a conventional plunger pump has been known that transfers fluid by rotating and reciprocating a plunger having a cut face on the outer periphery of its distal end in a cylinder chamber to let a suction port and a discharge port alternately communicate with the cylinder chamber.
If fluid that has characteristics of precipitation or depositing is transferred by such a plunger pump, precipitation or depositing may occur and disable sliding of the plunger in the cylinder and stop the pump. A plunger pump 100 disclosed in JP 2001-248543 A and JP 2008-51392 A as illustrated in FIG. 7, for example, includes depositing prevention ports 104a and 104b provided in a cylinder 101 at locations closer to the proximal end side than a suction port 102 and a discharge port 103 provided on the outer circumference of the cylinder 101 in the vicinity of the distal end.
Washing liquid is supplied from external to the depositing prevention ports 104a and 104b. The washing liquid washes away the fluid that has characteristics of precipitation or depositing from the clearance between the inner circumferential face 105 of the cylinder 101 and the outer circumferential face 106 of the plunger to prevent stopping of the pump caused by precipitation or depositing.
Under some operating conditions, such as the place where the pump is set and the operating environment, the washing liquid cannot be used or an additional flow passage for the washing liquid, including the depositing prevention ports 104a and 104b, cannot be provided. A plunger pump having a structure that can prevent stopping of the pump caused by precipitation or depositing regardless of the operating condition of the pump is desired.